Iontophoresis (e.g. Acta Dermatol venereol, vol. 64, p. 93, 1984) is a method of delivering a drug from the skin or mucosa using electric energy. In addition, there is also a method of extracting a diagnostic substance from a living body using the same principle, so as to observe the conditions of disease (e.g. Nature, Medicine, vol. 1, pp. 1198-120, 1995). In order to carry out these methods, an iontophoresis device having a desired structure is used as a device for delivering a bioactive substance, or as a device for extracting a diagnostic substance from a living body.
When an iontophoresis device that contains a chemically unstable drug is produced, it has been general to stabilize the drug by modifying the composition of its formulation. However, there are cases where such a drug cannot sufficiently be stabilized by devising the composition, because of the properties thereof. Thus, there has been proposed an iontophoresis device, wherein such a drug is conserved in a dry state and a liquid is then supplied to the dry drug when it is used.
For example, Patent Document 1 discloses an interface used for iontophoresis. In the case of this interface, a dry drug particle-adhered surface has been formed on one surface of a porous body, and when it is used, such a drug particle-adhered surface is allowed to come into contact with the skin of a living body. A hollow needle provided on a reservoir that contains a carrier solution is inserted into the reservoir from the top of a supporting member, so that they can be communicated with each other. Thus, the carrier solution is supplied to a porous body via the hollow needle and a conductive member. Thereafter, the conductive member is energized. The carrier solution permeates into the conductive member and the porous body, and it then reaches the drug particle-adhered surface. Thereafter, the carrier solution is mixed with the drug particle-adhered surface, so that they become a liquid. A liquid drug layer is formed on the skin surface of the living body, and the drug further permeates into the living body by electric force.
Patent Document 1: Japanese Patent No. 2795466
Patent Document 2 discloses a novel plaster structure used for iontophoresis. As shown in FIG. 4, this structure has such a structure that a capsule containing an electrolyte solution is provided in the upper portion of the plaster structure, and that a thin film such as an aluminum foil provided between the capsule and a water-containing layer is then destroyed when it is attached, thereby allowing the electrolyte solution to permeate therein, for example. When a water-degradable drug is used, it is said that it is adequate to provide a plaster structure, wherein a drug-containing layer and a water-containing layer are controlled in a dry state and which comprises a capsule containing an electrolyte solution.
Patent Document 2: Japanese Patent Publication No. 5-84180